Parametric Study of UC-PBG Structure in Terms of Simultaneous AMC and EBG Properties and its Applications in Proximity-coupled Fractal Patch Antenna

In this paper, a parametric study of conventional Uniplanar Compact Photonic Band Gap (UC-PBG) structures, with different dimensions, is investigated. The studied structure operates as an Artificial Magnetic Conductor (AMC) in which the performance is mainly characterized by the resonant frequency and bandwidth. Simulation and numerical analysis have been carried out using CST Microwave Studio software, which is based on Finite Difference Time Domain (FDTD), and Ansoft HFSS which is based on Finite Element Method (FEM). Results show that different dimensions affect the AMC\'s performance. The increase in the length and width of the UC-PBG slot will result in lower resonant frequencies and bandwidth degradation, while the frequency band position and the bandwidth will increase when the branch width have been increased. Furthermore, a prototype of a microstrip line proximity-fed to a fractal patch antenna on a UC-PBG substrate is designed and simulated. Computed results show that the antenna mounted on the UC-PBG substrate has over 9.2% wider impedance bandwidth than the same antenna etched on a grounded dielectric slab with same the same characteristics, due to in-phase reflection phase of UC-PBG structure. Compared with the reference antenna at 7.2 GHz, the back lobe is reduced by 7.86 dB in E plane and 7.68 dB in H plane. Cross-polarization level remains below -10 dB in both E and H planes.